G3 facsimile apparatuses based on ITU-T Recommendations T.30 exchange functional information pertaining to the capabilities of the apparatuses, e.g., a recording resolution, a printable main scan length, a sub-scan length, a coding scheme, a modulation scheme, a transmission rate, a sub-address, a password, and selective polling, by using DIC/DTC/DCS before transmission of documents. Therefore, if the functions of transmitting and receiving apparatuses are different, facsimile documents can be communicated by an optimum image format and communication method which both apparatuses have. Furthermore, facsimile services such as relay, broadcast, and polling can be performed by using the functions of sub-address, password, and selective polling.
To examine information about the result of communication performed by a facsimile apparatus, a communication result report shown in FIG. 12 is prepared. In facsimile communication, whether the communication is normally or abnormally terminated is known when the communication line is disconnected. Hence, a communication result is determined when a communication result report is output.
In communication apparatuses for communicating e-mail data, however, no means for exchanging information pertaining to such facsimile functional information is defined. Also, in e-mail data communication, no means for transmission acknowledgement (transmission result discriminating means) for indicating that transmission is reliably performed is defined.
Accordingly, to transmit e-mail by attaching facsimile-format image data, the general approach is to attach an image of a format, which is a base line (a minimum necessary function which a facsimile apparatus based on the ITU-T recommendations must have as essential capability) of G3 facsimile, to e-mail as image data of a TIFF format (a file format concerning raster image data developed by Aldus) by using, e.g., MIME or SMIME (an e-mail data format recommended by IETF). A coding scheme of the base-line image format is MH coding, its main scan resolution is 8 pels/mm, its sub-scan resolution is 3.85 lines/mm, and its original width is A4 208 mm.
If, therefore, the transmitting end transmits e-mail by attaching image data having higher resolutions, such as a main scan resolution of 16 pels/mm and a sub-scan resolution of 15.4 lines/mm, than the base line or by attaching image data of a large sheet size such as A3, it is unknown that the destination apparatus can process the received data. This makes it impossible to know whether the other party has reliably received the document.
Furthermore, since no means for communicating functional information concerning G3/G4 facsimile services is defined, facsimile services such as relay, broadcast, and polling cannot be used via e-mail communication.